Field of the Invention
The teachings in accordance with the exemplary embodiments presented by this disclosure generally relate to a head-up display (HUD) configured to project both two dimensional (2D) and three dimensional (3D) images.
Background of the Invention
In general, an instrument panel is installed next to a steering wheel to transmit vehicle related-information to a driver. The instrument panel is arranged to indicate engine revolution, current vehicle speed, engine temperature, amount of fuel and the like. Recently, the trend is that an analogue type instrument panel is changed to a digital type instrument panel to inform the driver of travel distance, fuel efficiency, mileage and other vehicle-related information.
Meantime, concomitant with generalization of position-based services using a commercial GPS (Global Positioning System), a navigation system capable of visually and audibly road-guiding a driver is mounted in a separate or a built-in manner in a vehicle. However, the navigation system is a hindrance to safe driving, because a driver must frequently move his or her view field from the vehicle's windshield to a navigation screen in order to view information transmitted by the navigation system. Furthermore, vehicle-related information other than travel path guide information must be obtained separately to scatter the view field when information on vehicle driving environment is to be checked.
In order to solve the aforementioned disadvantages, HUDs have been recently adopted for vehicles to provide various vehicle-related information during vehicle driving or airplane flying within a scope not deviating from a view field of a driver, (i.e., not deviating from a front view of the driver). The HUDs have been initially developed for providing flying information to an aviator by being mounted to an airplane, particularly to a fighter plane.
Thus, the vehicle-intended HUDs have been adopted from the principle of HUDs mounted on an airplane. The vehicle HUD includes a display unit having a projection screen, onto which vehicle information (speed, travel distance, RPM, etc.) of the instrument panel is projected on a front window within a view field of a driver by an image-producing unit and optionally by an optical module to allow the driver to easily learn the travel information even if the driver is in the midst of driving a vehicle, whereby the driver can drive safely by recognizing important travel information. Related patents can be found from Korea Registered Patents including Patent No. 10-1291408.
However, conventional HUDs are configured to provide only a two dimensional (2D) screen, which are limited to the presentation of simple drawings or character information on a limited size imaginary screen. Particularly, a HUD screen cannot help but be limited in size due to various regulations, and therefore is insufficient in size to provide a relatively large amount of information including travel guide. Furthermore, a virtual image enlarged by an optical system is formed by being fixed to a designed depth to allow transmission of only 2D information. Of course, although technical ideas of adding other virtual images have been disclosed by improving the optical system, this type of configuration suffers from disadvantages of decreased daytime visibility due to loss of light caused by structural limits, and position of virtual images cannot but be fixed. Thus, demand on development capable of providing more information within a limited size of screen is required.